Front wheel cargo hub advice

[chris667]

Hello

I have a Pashley Mailstar which I am planning to electrify, like this one:



It is heavy and strong. Not that good a bike honestly, but excellent for carrying bulky items.

I was thinking of electrifying it for use as a shopping/allotment bike.

The front Sturmey drum brake is actually quite good in that 507 wheel, but I'm thinking that I would like to fit a front hub and braze on disc mounts to the (very beefy) steel forks.

What would be a good front hub for this application? I don't want to go faster than 15mph, there will always be a good bit of weight in the front but there are steep hills here - some as much as 15%.

I am happy to muscle this out with my DWGC22 on an old mountain bike, but I'd like to do less work with this one. Total weight of rider, bike and tools is about 140KG.

Also, what's the most minimal controls available? I would prefer not to have an LCD - just a pedal sensor and something for switching between power levels. I have other bikes for distances, this is for general local transport.

In short:

Low speed
High torque
Range <=15 miles - no need for a massive battery.

Price is not that important - not having a car means I can afford this!

I do know I could fit a BB motor (Pashley still sell this bike with a BBS01), but I prefer the simplicity of the hub motor on the front wheel.

 

[Chalo]

That's a very modest speed goal. I think you should consider using a motor/voltage/current that gives a free speed of about 30 mph. Hear me out.

If you only want or need 15 mph, you might as well be able to maintain that much speed in the widest range of conditions. If the bike naturally cruises at 15 in flat smooth conditions, it will slow down dramatically from hills, headwinds and such. A motor/battery/controller combination that runs at 30 mph unloaded will be capable of putting out its maximum power at 15 mph more or less. So if you electronically limit the speed to 15 mph, it will have enough power available to climb reasonable slopes at 15, accelerate quickly up to that speed, or buck headwinds and rough surfaces at top speed.

A Bafang BPM would be about the least amount of geared hub motor I'd use for the job you describe. A Leaf "1500W" motor with a nice high turn count would also do the job, even if you never fed it nearly as much as its rated power.

I know KT controllers are configurable enough to do precise speed limiting, various throttle ramp-up rates, and other features you will probably want in a heavy front drive bike.

 

[chris667]

I certainly can see what you're getting at.

 

[Chalo]

Another idea, if you have access to salvage parts from dockless rental e-bikes, is to use two motors. Most of those bikes are front motored, but you can add a rear motor of about the same spec for twice the torque (but barely more speed).

I can't really tell what's going on with the rear gears of that Pashley, but if you have two hub motors your pedal gearing won't matter all that much.

 

[hypersphere]

but there are steep hills here - some as much as 15%

On my bicycle I calculated without any extra weight on the front, I would just barely not be able to make it up a 15% grade. So long as you add cargo in the front first, I think you can pull this off.

 

[chris667]

I can't really tell what's going on with the rear gears of that Pashley, but if you have two hub motors your pedal gearing won't matter all that much.

It has Sturmey archer drums front and rear, the rear is a 3-speed, spaced at 120mm.

The frame at the rear is a loop - if I was to replace the rear hub I don't believe I could braze on a disc tab anywhere. I think it would be feasible to put cantilever studs on the middle seatstay and fit a Magura type rim brake though.

I do like the idea of a 2WD bike. Are there any rear hubs which have narrower spacing?

On my bicycle I calculated without any extra weight on the front, I would just barely not be able to make it up a 15% grade. So long as you add cargo in the front first, I think you can pull this off.

Definitely cargo front first and battery front first. They handle really badly without weight in the front!

Like a say, Mailstars are weird bikes.

Edit - had a look - what hub are you running, @hypersphere ?

 

[LewTwo]

I have had several front hub e-bikes but always with fairly level terrain. Having said that the other 'gotcha' to consider is the road surface. With most of the weight on the ass end the front hubs tend to spin on loose surfaces (i.e. gravel, sand, etc). Not so much a problem on hard surfaces (i.e. clean, solid pavement).

 

[Mclewis1]

Modifying the rear end is likely going to be required if you want to go 2WD. Do you know if Pashley modifies (widens) the rear end when they build the BBS01 mid drive version? Ideally (for the highest power) you'd want a front hub/mid drive combination. There are/were some 120mm rear hubs but they are rare and now only appear to be available as salvaged items from older bikes. I don't think going this route would make sense unless you could find a unicorn (essentially an unused geared rear hub with 120mm spacing). Another option would be widening the rear dropouts on your bike to accommodate a more popular 135mm spacing so you'd have some good rear hub choices with the possibility of adding a derailleur and gearing. Being a steel frame it should be possible to widen the rear dropouts without compromising the frame.

Another option is a larger more powerful front hub motor only setup. Have a look at the Grin all axle motor, and specifically the Front All Axle Barebones kit. Grin Front All-Axle Barebones Kit It's certainly not cheap, but it's very high quality, easily configurable, and can be bought as a complete setup (motor, integrated controller, wiring, throttle, and battery) making the installation very simple.

It would be interesting to see if a downtube battery will fit on the Mailstar's frame in the traditional downtube position (and it looks like it would be helpful to raise the position of the battery a little bit to gain some extra room from the angled chainstays). If there's enough room you'll need to add some mounting points (using Rivnuts or similar to create the 4-5mm threaded mounting points) - another option is to use robust straps, and this might be a good choice to try it all out (before drilling the frame). A downtube mounted battery will keep the center of gravity lower which will be helpful when you are adding weight higher up on those front and rear racks/baskets.

Yes the All-Axle motor is a direct drive (and not geared) hub motor and so it's not an optimal design for climbing, but what it gives up to a geared motor (better internal rpm) it makes up for with raw power and reliability when pushed hard. The L10 connected BaseRunner controller and a good battery will give you lots of power for this motor (1500w+ continuous). The choice of a 36, 48 or 52v battery will determine your top speeds. The "barebones" kits contain a simple thumb or twist throttle with a small integral display that shows you voltage so you can accurately estimate your battery's current condition.

The Grin simulator shows this motor on a very heavy 375lb bike with 26" wheels will still climb a 10% grade at 14mph for at least 6 minutes before overheating (assuming a STD wind motor with Statoraide). With more realistic loads and maybe a bit more human input (more than 100w) you should be able to climb just about any hill. What it probably won't do is climb the rare really long (multi mile) steep (10+ %) inclines.

 

[Chalo]

I think it would be feasible to put cantilever studs on the middle seatstay and fit a Magura type rim brake though.

Any linear pull brake would be very effective (more than the drums you have now) and much easier to live with than Magura hydraulic rim brakes. While it's true that those are among the very most powerful brakes you can use, they're easily the worst I've ever had to set up or adjust-- and they've gotten worse in that regard over the last 30 years.

I do like the idea of a 2WD bike. Are there any rear hubs which have narrower spacing?

There are some 120mm spaced, freewheel threaded hub motors out there for single speed bikes.

Single Speed 24V 36V 250W Electric Bike Hub Motor Conversion Kit for Rear Drive | eBay

Single Speed 24V36V 250W Electric Bike Hub Motor Conversion Kit Accelerator Handle For E-Bicycle Rear Drive Wheel. 1x 250W brushless hub motor ( for back wheel ). 1x Thumb throttle (with battery indicator lights & button switch).

www.ebay.com

 

[Mclewis1]

Hey, Chalo found my 120mm "unicorn" in kit form. Unfortunately single speed only (not good for climbing), but I guess it might be possible to also find a narrow freewheel cluster (a serious 1960/70s road bike setup).

 

[Chalo]

Hey, Chalo found my 120mm "unicorn" in kit form. Unfortunately single speed only (not good for climbing), but I guess it might be possible to also find a narrow freewheel cluster (a serious 1960/70s road bike setup).

Note that because of the big flat side cover, you might or might not be able to use the innermost sprocket of a 3 or 4 speed freewheel. My own QS 212 hub motor was advertised as being compatible with a 3 speed freewheel, but of the 16-19-22 sprockets, I can only use the 16 and 19 tooth ones, because the 22 runs too close to the side cover to . allow the chain to engage it. If I'd known that in advance, I would have fitted a single freewheel and been done with it.

Mind you, that's a great big flat motor with a negligible "snout" for the freewheel thread, and the motor you found might not have the same issue.

I think if you use an appropriate single gear for unpowered city use, and you have two hub motors working, you won't have any problems climbing. It would only become a problem if one or both motors are out of action.

 

[chris667]

While it's true that those are among the very most powerful brakes you can use, they're easily the worst I've ever had to set up or adjust-- and they've gotten worse in that regard over the last 30 years.

I really like them! They are very fiddly to set up, but the beauty of Maguras is once they're done, they're done. Just change the pads every 8,000 miles, and replace rims as they wear out.

 

[chris667]

Modifying the rear end is likely going to be required if you want to go 2WD. Do you know if Pashley modifies (widens) the rear end when they build the BBS01 mid drive version? Ideally (for the highest power) you'd want a front hub/mid drive combination. There are/were some 120mm rear hubs but they are rare and now only appear to be available as salvaged items from older bikes. I don't think going this route would make sense unless you could find a unicorn (essentially an unused geared rear hub with 120mm spacing). Another option would be widening the rear dropouts on your bike to accommodate a more popular 135mm spacing so you'd have some good rear hub choices with the possibility of adding a derailleur and gearing. Being a steel frame it should be possible to widen the rear dropouts without compromising the frame.

Looking at the e-Pronto's page (the modern, electric Mailstar), I see it has the same hub - the only difference I can tell is the e-Pronto has an aheadset. GBP£2,500 for a bike with a BBS01!

I think widening the frame for a rear hub is going to be the best solution, and as I'm going to braze canti studs onto one of the sets of seatstays, I might as well have a go, why not? For some reason only known to Pashley, the dropout actually has a hole for a mech hanger with a separate threaded hole for the (weird!) chain tensioner so it would be relatively easy to do a build with a wide range cassette.

Battery's going in the front rack - it doesn't turn with the bars and like I say it really improves the handling to have some weight there. I like that potentially if it was FWD only I could have really short cable runs.

 

[Chalo]

They are very fiddly to set up, but the beauty of Maguras is once they're done, they're done.

I find that there's a lot more fiddling to do along the way as pads wear. I tried them first on my own bike in '93 or '94, but soon decided they weren't worth it. Yet somehow each successive generation of those things seems to get worse to set up and adjust.

 

[hypersphere]

Edit - had a look - what hub are you running, @hypersphere ?

Well, I'm still on a BionX kit but I'm planning on a GMAC on the rear of a Dahon Mu P8 with enough power to pull my kids in a trailer. Unlike carrying extra weight on the bike, the trailer means you need more force to climb the hill while not assisting in downforce to get more traction, making a front hub pretty useless even before you account for the rain...